1. Field of the Invention
The present invention is related to a wiring board with a built-in electronic component in which an electronic component such as a semiconductor element is accommodated.
2. Discussion of the Background
In recent years, electronic devices have become more highly functional and compact. Accordingly, wiring boards mounted inside such electronic devices are further required to be highly functional and highly integrated.
For example, in Japanese Patent Laid-Open Publication 2002-246757, a method for manufacturing a multilayer printed wiring board is described as follows: a step to laminate a sheet such as a UV tape on the bottom of a penetrating hole formed in a core substrate; a step to mount a semiconductor element such as an IC chip on the sheet in such a way that its terminals contact the adhesive surface of the sheet; a step to fill resin in the penetrating hole; a step to cure the filled resin; a step to remove the sheet; and a step to form build-up layers on the top surface of the semiconductor element.
As shown in FIG. 13A, the UV tape or the like may likely warp. Furthermore, if the laminated UV tape or the like is warped, sealing on the bottom side becomes incomplete. Accordingly, as shown in FIG. 13B, filling resin may seep into the gaps between the core substrate and the UV tape or the like. The contents of this publication are incorporated herein by reference in their entirety.